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Orange Moss Agaric - Rickenella fibula

Good evening, friends,

This week's mushroom is Rickenella fibula, commonly known as the orange moss agaric, and formerly known as Omphalina fibula. The best Mushroom Mondays are the freshest and that's what we have here tonight. That's what we've earned here tonight. The gentle rain last night was able to coax the moss into divulging some of its secrets, and that's why we get to look at this ephemeral little fellow. I found this mushroom - along with a host of other diminutive mushrooms that popped up after the rain - while walking the trails at Manitou this morning.

Rickenella fibula

Fun Facts

This fungus is a bryophyte - it loves moss - and it's quite possible the moss loves this fungus too. It's not fully understood, but it is believed that this fungus lives within the moss in a mutualistic relationship, but can also act as a saprobe and help decompose the moss fruiting bodies. More on that later. The whispy tufts of moss at the base of the mushroom are broom moss (Dicranum), while the fern-like fronds of moss beneath them looks like the common fern moss (Thuidium delicatulum).

The mushroom has been found growing in terrariums. By virtue of that, I imagine this fungus is quite hardy and widespread. Nonetheless, this was the only R. fibulamushroom I could see in the area. I decided not to pluck it from its comfy moss covers so that it could continue to release spores locally.

Rickenella fibula


As mentioned previously, this mushroom is likely saprobic, but may also form some sort of symbiosis with moss. Per the US Department of Energy Joint Genome Institute, "analyses of R. fibula’s metatranscriptomes have revealed that it is active throughout photosynthetic and senescent bryophyte tissues". The fungus winds its way through the plant cells and is living within the moss - challenging the concept of how you define individual organisms. Would the moss be able to live without the fungus and vice versa - would the fungus live without the moss? It's fun to think about.

The government also notes that the mushroom grows from the "senescing portions of bryophyte gametophytes" which translates to 'the decaying reproductive parts'. This is why it is suspected to also be saprotrophic (sapro meaning dead and trophe meaning nourishment) - getting its nutrients from the dead parts of the moss as well as the living. Since it is found in both living and dead moss it could even be parasitic - there isn't any definitive science on the relationship between the two yet.

Rickenella fibula

The above photo shows the gills are decurrent, meaning they run down the stipe, and said gills can vary in color from white to pale orange. The mushroom grows spring through fall and can even be found throughout winter in warmer climes. It's been recorded on five continents with Africa and Antarctica as the two exemptions. However, there are a couple similar species, so perhaps there are misidentified observations influencing the wide-range of this mushroom. In the northeast, the spring appearance and the mutualism with moss are helpful identifying factors.

More Mushrooms

Here are some pictures of other mushrooms I found today, starting with these beautiful boletes:


These Gymnopus fruiting from an acorn:


These little Marasmius, from what I could deduce they were M. rotula:


A polypore we may look at more closely next week. It can be used to dye wool and other fabrics, Hapalopilus rutilans:

Hapalopilus rutilans


1) Kuo, M. (2016, January). Rickenella fibula. Retrieved from the MushroomExpert.Com Web site:


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